Require CMake 3.4 at least.

CMakeLists.txt

@@ -23,14 +23,9 @@
 #   DEALINGS IN THE SOFTWARE.
 #
 
-cmake_minimum_required(VERSION 3.1)
-
-# Configuration fails on < 3.4 if only C++ is enabled (CheckFunctionExists
-# macro called from FindX11)
-if(NOT CMAKE_VERSION VERSION_LESS 3.4.0)
-    set(LANG CXX)
-endif()
-project(MagnumBindings ${LANG})
+cmake_minimum_required(VERSION 3.4)
+
+project(MagnumBindings CXX)
 
 # Use folders for nice tree in Visual Studio and XCode
 set_property(GLOBAL PROPERTY USE_FOLDERS ON)

package/ci/travis.yml

@@ -100,12 +100,12 @@ install:
 - if [ "$BUILD_STATIC" != "ON" ]; then export BUILD_STATIC=OFF; fi
 - if [ "$TRAVIS_OS_NAME" == "linux" ] && ( [ "$TARGET" == "desktop" ] || [ "$TARGET" == "desktop-sanitizers" ] ); then export PLATFORM_GL_API=GLX; fi
 - if [ "$TRAVIS_OS_NAME" == "linux" ] && [ "$TARGET" == "desktop-gles" ]; then export PLATFORM_GL_API=EGL; fi
-# Download CMake 3.1.3 to ensure we're still compatible with it (Travis has
+# Download CMake 3.4.3 to ensure we're still compatible with it (Travis has
 # 3.9 since December 2017). Also, the PATH setting can't be cached, so it's
 # separate (bit me two times already). Android needs CMake 3.7, but
 # https://gitlab.kitware.com/cmake/cmake/issues/17253 is fixed in 3.9.2, so
-# grab that. FindVulkan is since 3.7, in that case just use the system package.
-- if [ "$TRAVIS_OS_NAME" == "linux" ] && [ ! -e "$HOME/cmake/bin" ]; then cd $HOME ; wget -nc --no-check-certificate https://cmake.org/files/v3.1/cmake-3.1.3-Linux-x86_64.tar.gz && mkdir -p cmake && cd cmake && tar --strip-components=1 -xzf ../cmake-3.1.3-Linux-x86_64.tar.gz && cd $TRAVIS_BUILD_DIR ; fi
+# grab that.
+- if [ "$TRAVIS_OS_NAME" == "linux" ] && [ ! -e "$HOME/cmake/bin" ]; then cd $HOME ; wget -nc --no-check-certificate https://cmake.org/files/v3.4/cmake-3.4.3-Linux-x86_64.tar.gz && mkdir -p cmake && cd cmake && tar --strip-components=1 -xzf ../cmake-3.4.3-Linux-x86_64.tar.gz && cd $TRAVIS_BUILD_DIR ; fi
 - if [ "$TRAVIS_OS_NAME" == "linux" ]; then export PATH=$HOME/cmake/bin:$PATH && cmake --version; fi
 - if [ "$TRAVIS_OS_NAME" == "osx" ]; then HOMEBREW_NO_AUTO_UPDATE=1 brew install ninja; fi